Neuroscientists create intercontinental mind meld between two rats

It's not exactly a Vulcan mind meld, but it's not far off.
Scientists have wired the brains of two rats together and shown
that signals from one rat's brain can help the second
rat solve a problem it would otherwise have no clue how to
solve.

The rats were in different cages with no way to communicate
other than through the electrodes implanted in their brains.
The transfer of information from brain to brain even worked with
two rats separated by thousands of kilometres, one in a lab in
North Carolina and another in a lab in Brazil.

"We basically created a computational unit out of two brains,"
says neuroscientist Miguel Nicolelis of Duke University, who led
the study.

Nicolelis is a leading figure in brain-machine interface
research and the man behind a bold plan to develop a brain-controlled exoskeleton that would
allow a paralysed person to walk onto the field and kick a soccer
ball at the opening ceremony of next year's World Cup in
Brazil.

He says the new findings could point the way to future
therapies aimed at restoring movement or language after a stroke or
other brain injury by using signals from a healthy part of the
brian to retrain the injured area. Other researchers say it's
an interesting idea, but it's a long way off.

But Nicolelis's group is known for pushing the envelope.
Previously, they have given monkeys an artificial sense of touch they can use to distinguish the
"texture" of virtual objects. More recently, they gave rats
the ability to detect normally invisible infrared light by
wiring an infrared detector to a part of the brain that processes
touch. All this work, Nicolelis says, is relevant to developing
neural prostheses to restore sensory feedback to people with brain
injuries.

In the new study, the researchers implanted small electrode
arrays in two regions of the rats' brains, one involved in planning
movements, and one involved in the sense of touch.

Then they trained several rats to poke their noses and whiskers
through a small opening in the wall of their enclosure to determine
its width. The scientists randomly changed the width of the
opening to be either narrow or wide for each trial, and the rats
had to learn to touch one of two spots depending on its width.
They touched a spot to the right of the opening when it was wide
and the spot on the left when it was narrow. When they got it
correct, they received a drink. Eventually they got it right 95
percent of the time.

Next, the team wanted to see if signals from the brain of a rat
trained to do this task could help another rat in a different cage
choose the correct spot to poke with its nose - even if it had no
other information to go on.

They tested this idea with another group of rats that hadn't
learned the task. In this experiment, one of these new rats sat in
an enclosure with two potential spots to receive a reward but
without an opening in the wall. On their own, they could only guess
which of the two spots would produce a rewarding drink. As
expected, they got it right 50 percent of the time.

Then the researchers recorded signals from one of the trained
rats as it did the nose-poke task and used those signals to
stimulate the second, untrained rat's brain in a similar pattern.
When it received this stimulation, the second rat's performance
climbed to 60 or 70 percent. That's not nearly as good as the rats
who could actually use their sense of touch to solve the problem,
but it's impressive given that the only information they had about
which spot to chose came from another animal's brain, Nicolelis
says.

Both rats had to make the correct choice, otherwise neither one
got a reward. When that happened, the first rat tended to make
its decision more quickly on the next trial, and its brain activity
seemed to send a clearer signal to the second rat, the
team reports
today in Scientific Reports. That suggests
to Nicolelis that the rats were learning to cooperate.

The brain-to-brain communication link enables the rats to
collaborate in a novel way, he says. "The animals compute by
mutual experience," he said. "It's a computer that evolves,
that's not set by instructions or an algorithm."

From an engineering perspective, the work is a remarkable
demonstration that animals can use brain-to-brain communication to
solve a problem, said Mitra Hartmann, a biomedical engineer who
studies rats' sense of touch at Northwestern University. "This is a
first, to my knowledge, although the enabling technology has
been around for a while."

"From a scientific point of view, the study is noteworthy for
the large number of important questions it raises,
for example, what allows neurons to be so 'plastic' that the
animal can learn to interpret the meaning of a
particular stimulation pattern," Hartmann said.

"It's a pretty cool idea that they're in tune with each other
and working together," said neuroscientist Bijan Pesaran of New
York University. But Pesaran says he could use some more convincing
that this is what's actually going on. For example, he'd like to
see the researchers extend the experiment to see if the rats on the
receiving end of the brain-to-brain communication link could
improve their performance even more. "If you could see them
learning to do it better and faster, then I'd really be
impressed."

Pesaran says he's open to the idea that brain-to-brain
communication could one day be used to rehabilitate brain injury
patients, but he thinks it might be possible to accomplish the same
thing by stimulating the injured brain with computer-generated
patterns of activity. "I don't get why you'd need another
brain to do that," he said.